1. Field of the Invention
The present invention relates to a toner/developer mixing roller and developing device for a laser printer, and more particularly, to a toner/developer mixing roller disposed in a developing device to mix toner and a developer in a laser printer.
2. Description of the Related Art
Generally, a laser printer comprises a printer body, a developing device disposed in an inside of the printer body with a photoconductive drum, a laser scanning unit projecting a laser beam to the photoconductive drum to form an electrostatic latent image thereon, and a toner supply unit supplying toner to develop the electrostatic latent image formed on the photoconductive drum.
The developing device comprises a housing supporting the photoconductive drum to rotate while being in contact with a preselected transfer roller, a charging unit disposed in the inside of the housing to charge the photoconductive drum, a developing roller transferring the toner supplied to the inside of the housing to the photoconductive drum, and a cleaning blade removing used toner remaining on the developing roller and photoconductive drum.
The toner supply unit is removably disposed at a printer body of the laser printer. The toner supply unit has a toner cartridge having a toner discharger and new toner stored inside thereof. The toner cartridge is disposed at the printer body as being connected to the housing through a preselected toner supply passage. The toner cartridge is generally disposable, and thus, after being used up, it is replaced by a new one.
For a developing operation of the above construction, the toner stored in the toner cartridge is supplied to the inside the housing of the developing device through the toner supply passage.
A developing device for a binary developer comprises a toner/developer mixing roller mixing supplied toner with a developer or a carrier, which is prepared inside the housing. The mixing roller disposed inside the housing rotates to mix the developer prepared inside the housing with the toner supplied to the inside the housing and then transferred by a preselected toner supply roller.
FIG. 1 is a perspective view schematically showing a toner/developer mixing roller 10 of a conventional laser printer. Referring to FIG. 1, the mixing roller 10 includes a hollow body 11, on which ribs 13 are formed along a longitudinal direction of hollow body 11 at predetermined intervals, that is, slits 15 alternating with the ribs 13 are formed. The ribs 13 slant to one direction with respect to the longitudinal direction, that is, in a spiral form. The mixing roller of this shape rotates to mix the toner and the developer, thereby supplying the mixture to a developing roller.
A concentration distribution of the toner and the developer in the mixture is not uniform due to the intervals of the ribs 13.
The spiral slant of the ribs causes the mixture of the developer and the toner contained in the inside of the housing to cluster together on a side of the housing or the mixing roller 10. This causes a problem that an intensity of a developed image is uneven across a sheet of paper besides the cluster problem occurring due to the intervals of the ribs 13.